1. Field of the Invention
The present invention relates to a headrest device for a vehicle seat, and more particularly to a headrest device of the type which includes a headrest body which can be adjustably displaced in a forward or backward relationship with respect to the back of the vehicle seat.
2. The Prior Art
A hitherto known headrest device of the type which includes a headrest body whose position is adjustable in a forward or backward relationship relative to a seat back is typically constructed such that the headrest body, which is constructed to have an egg-shaped cross-sectional configuration, is pivotally supported at a position located eccentrically relative to the device, and includes a gearing mechanism arranged between the headrest body and the pivotal support portion. The gearing mechanism operates such that a gear on the headrest body is normally brought in meshing engagement with a gear on the pivotal support portion so that the angular position of the headrest body can be adjusted as required, i.e., by rotating a knob on the headrest body. This results in the headrest body being properly located relative to the seat back.
Although the headrest body of such a conventional headrest device can satisfactorily resist an impulsive load induced by a driver's head in the event of a collision, owing to the meshing gear connection between the headrest body and the pivotal support portion of the device, it has been found that such a headrest device has the drawback that a number of rotations of the knob are required in order to adjust the angular position of the headrest body, making it difficult to achieve a quick angular adjustment thereof. Another drawback of the conventional headrest device is that the point where the driver's head comes in contact with the headrest body varies in accordance with the inclination of the headrest body and thereby the geometrical configuration of the contact area varies correspondingly, resulting in an uncomfortable feeling for the driver.